Evaluation of the atmospheric water vapor content in a regional climate model using ground-based GPS measurements

Abstract. In this paper, we compare the diurnal variations in middle-atmospheric water vapor as measured by two ground-based microwave radiometers in the Alpine region near Bern, Switzerland. The observational data set is also compared to data from the chemistry–climate model WACCM. Due to the small diurnal variations of usually less than 1%, averages over extended time periods are required. Therefore, two time periods of five months each, December to April and June to October, were taken for the comparison. The diurnal variations from the observational data agree well with each other in amplitude and phase. The linear correlation coefficients range from 0.8 in the upper stratosphere to 0.5 in the upper mesosphere. The observed diurnal variability is significant at all pressure levels within the sensitivity of the instruments. Comparing our observations with WACCM, we find that the agreement of the phase of the diurnal cycle between observations and model is better from December to April than from June to October. The amplitudes of the diurnal variations for both time periods increase with altitude in WACCM, but remain approximately constant at 0.05 ppm in the observations. The WACCM data are used to separate the processes that lead to diurnal variations in middle-atmospheric water vapor above Bern. The dominating processes were found to be meridional advection below 0.1 hPa, vertical advection between 0.1 and 0.02 hPa and (photo-)chemistry above 0.02 hPa. The contribution of zonal advection is small. The highest diurnal variations in water vapor as seen in the WACCM data are found in the mesopause region during the time period from June to October with diurnal amplitudes of 0.2 ppm (approximately 5% in relative units).

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Diurnal variations in middle atmospheric water vapor by ground-based microwave radiometry

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-3859-2013 ◽

2013 ◽

Vol 13 (2) ◽

pp. 3859-3880 ◽

Cited By ~ 1

Author(s):

D. Scheiben ◽

A. Schanz ◽

B. Tschanz ◽

N. Kämpfer

Keyword(s):

Water Vapor ◽

Observational Data ◽

Climate Model ◽

Correlation Coefficients ◽

Diurnal Variations ◽

Atmospheric Water Vapor ◽

Atmospheric Water ◽

Data Set ◽

Diurnal Variability ◽

Time Periods

Abstract. In this paper, we compare the diurnal variations in middle atmospheric water vapor as measured by two ground-based microwave radiometers in the Alpine region near Bern, Switzerland. The observational data set is also compared to data from the chemistry-climate model WACCM. Due to the small diurnal variations of usually less than 1%, averages over extended time periods are required. Therefore, two time periods of five months each, December to April and June to October, were taken for the comparison. The diurnal variations from the observational data agree well with each other in amplitude and phase. The linear correlation coefficients range from 0.8 in the upper stratosphere to 0.5 in the upper mesosphere. The observed diurnal variability is significant at all pressure levels within the sensitivity of the instruments. Comparing our observations with WACCM, we find that the agreement of the phase of the diurnal cycle between observations and model is better from December to April than from June to October. The amplitudes of the diurnal variations for both time periods increase with altitude in WACCM, but remain approximately constant at 0.05 parts per million in the observations. The WACCM data is used to separate the processes that lead to diurnal variations in middle atmospheric water vapor above Bern. The dominating processes were found to be meridional advection below 0.1 hPa, vertical advection between 0.1 and 0.02 hPa and (photo-)chemistry above 0.02 hPa. The contribution of zonal advection is small. The highest diurnal variations in water vapor are found in the mesopause region during the time period from June to October with diurnal amplitudes of 0.2 ppm (approximately 5% in relative units).

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Retrieving atmospheric water vapor content based on absolute brightness of sky background spectral radiation

Fifth Conference on Frontiers in Optical Imaging Technology and Applications ◽

10.1117/12.2506466 ◽

2018 ◽

Author(s):

xiao Ma ◽

Haiping Mei ◽

Ruizhong Rao

Keyword(s):

Water Vapor ◽

Water Vapor Content ◽

Atmospheric Water Vapor ◽

Atmospheric Water ◽

Spectral Radiation ◽

Absolute Brightness

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The determination of the total atmospheric water vapor content over the oceans using the MTVZA-GY microwave radiometer measurements

Вычислительные технологии ◽

10.25743/ict.2020.25.4.008 ◽

2020 ◽

pp. 83-98

Author(s):

Анжелика Андреевна Косторная ◽

Алексей Николаевич Рублев ◽

Владимир Викторович Голомолзин

Keyword(s):

Water Vapor ◽

Approximation Error ◽

Water Vapor Content ◽

Atmospheric Water Vapor ◽

Microwave Range ◽

Adaptive Search ◽

Atmospheric Water ◽

Water Vapor Absorption ◽

Optimal Set

Представлена методика определения интегрального влагосодержания в безоблачной атмосфере над океанскими и морскими акваториями по измерениям микроволнового радиометра МТВЗА-ГЯ, устанавливаемого на российских гидрометеорологических спутниках серии “Метеор-М”. Определение влагосодержания осуществляется с помощью регрессий, предикторами которых являются измеренные интенсивности излучения в выбранных каналах радиометра. В их число могут входить каналы с рабочими спектральными диапазонами внутри и вне полос поглощения водяного пара. Адаптивный поиск оптимального набора каналов для различных районов земного шара проводится в зависимости от типа поверхности и климатической зоны. Критерием выбора каналов и вида регрессии является минимальная среднеквадратичная невязка получаемых оценок влагосодержания атмосферы с контрольными значениями, рассчитанными по данным реанализа Национального центра экологического прогнозирования (NCEP) и специальных атмосферных моделей, разработанных в Европейском центре среднесрочных прогнозов погоды (ECMWF) The determination of the total atmospheric water vapor content over the cloudless ocean using the MTVZA-GY measurements in microwave range is described. The microwave scanning radiometer MTVZA-GY is located on the Russian meteorological satellites “Meteor-M” and outgoing radiation of the surface-atmosphere system is measured in 29 channels. To calculate the integrated water vapor, the adaptive searching of the optimal set of channels using regression analysis was proposed. Frequencies that are not related to water-vapor absorption lines are used as predictors. The minimum of total approximation error was obtained for selected channels and corresponding regression coefficients values. The quality control of retrieval integrated water vapor (kg/m) was conducted with the help of the set of atmospheric profiles obtained by M. Matricardi and NCEP/NCAR Reanalysis as a priori data using the proposed method. Standard deviations (RMS) obtained by determined adaptive search for the predictors are about 3 kg/m2. Application of the method for cloudless water areas allowed finding a set of 6 channels MTVZA GY (18.7H, 23.8V, 23.8H, 57+0.32+0.025H, 57+0.32+0.01H и 183+1.4V) for which the RMS values are minimal - 4.4 kg/m. The use of all channels of the device in the search allows reducing the error in determining the integrated water vapor content. The proposed method for recovering the content of water vapor from measurements in the channels of the MTVZA-GYa device allows an adaptive search for an optimal set of channels for different regions of the globe and find the best combinations for various climatic zones and surface types

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